I've never actually seen the real number, and the commenter didn't give one, but 50 million certainly seems likely to have been a vast overstatement.

But the actual science has been quite good. Consider this: the IPCC's First Assessment Report (1990) includes projections of sea level rise for the period 1985-2030 (Ch9 Table 9.10 pg 276):

(This looks like a digital scan of the all the original, and apparently the decimal points didn't cut it.)

How does this compare to reality? Well, it's not 2030 yet, but Aviso data on sea level show an average rate of (linear) change for the 22.8 years of their data (1993.00 to 10/25/15) is 3.34 mm/yr. So for the 45 years considered in the FAR above, that works out to a projection (if linear) of 15.0 cm.

Compare to their "best estimate" of 18.3 cm. Pretty damn good, especially when you consider that the scientific projections, which aren't linear as theyinclude sea level rise acceleration, will likely be more than my number, so closer to the "Best Estimate" above, if not beyond it.

It's undoubtably very difficult to project what people will do in response to specific aspects of climate change -- there aren't many laws or equations in sociology. The UNEP and UNU were probably reckless in making such a projection, even over a short time period. It would be interesting to understand how they were so wrong, and der Spiegel does some of that here.

32 comments:

Thanks for the link, David. There have been a large number of failed climate predictions. This site lists 107 of them, as of 2014. http://wattsupwiththat.com/2014/04/02/the-big-list-of-failed-climate-predictions/ The many failed predictions cause some people to discount all climate concerns. It's like the story of the Boy Who Cried Wolf. That's unfortunate, since some of the concerns are real.

David's link gives a clue as why there are so many failed predictions. People sometimes state bad consequences as facts, when they're just speculation. Sometimes certain assertions of bad consequences go beyond the science or even contradict the theory or the facts on the ground. Here are a couple of examples, from David's link.

-- In October 2005, United Nations University said: "such problems as sea level rise, expanding deserts and catastrophic weather-induced flooding have already contributed to large permanent migrations and could eventually displace hundreds of millions." AFAIK it's by no means established that climate change had caused any increase in weather-induced flooding. Both theory and data say that global warming is likely to shrink deserts, not expand them, since greater ocean evaporation leads to more rainfall.

-- The UNEP spokesman said land degradation, the loss of forests and other environmental changes were accelerating. In fact, forested land has been increasing, not shrinking. E.g., see http://www.un.org/apps/news/story.asp?NewsID=37845#.Vq7s2rIrJD8 Presumably the cause is greater rainfall and more atmospheric CO2.

I can't recall where but I've seen figures which support a number in the ballpark of 50 million environmental "refugees", though they are mostly internally displaced, which is where the controversy comes in since those moving within a country typically aren't called "refugees" in common parlance.

On FAR sea level projection, note that the "Business as Usual" scenario assumed substantial continuing increases in CFCs and methane, which largely didn't happen. The total historical forcing level to 2015 under this (GHG-only) scenario is about 30% greater than currently understood observed GHG forcing at 2015, and the observed forcing change from 1985 to 2015 is about 50% of that used in the scenario.

I agree with Harry Twinotter, a website that specialises in conspiracy lunacy is not worth perusing. Also a site that has never applied any self-evaluation to its own predictions - how many predictions of imminent global cooling, fake pauses and reversal of Arctic sea ice shrinkage appeared on the same site?

Harry -- ad hominem is fallacious reasoning. Even if you don't like Watts, you could check his list and discover for yourself that there are lots of failed predictions from warmists.

Unknown 5:36, you make a good point. There are lots of failed predictions from deniers, too. OTOH climate skeptics seldom make failed predictions. In fact, they seldom make predictions. They tend to say that we don't know enough to predict.

From D.i.C."Even if you don't like Watts, you could check his list and discover for yourself that there are lots of failed predictions from warmists."

How can you post such utter nonsense here? Not a single "prediction" has a link to it, but here's just a few of the so-called 'failed predictions'

"The ski areas that reliably have snow will shift from 1200 meters to 1500 meters elevation by the year 2050; because of the climate prognoses warmer winters have to be anticipated.”

Riiiiggggghhhhtt. Because it is so much the year 2051 and the prediction has failed to come true.

“Warm in the winter, dry in the summer … Long, hard winters in Germany remain rare: By 2085 large areas of the Alps and Central German Mountains will be almost free of snow."

Yes! It's the year 2086 and this definitely hasn't come true. Another failed prediction!

Let's do one more:“By the year 2050 … temperatures will rise 1.5ºC to 2.5°C (summer) and 3°C (winter). … in the summer it will rain up to 40% less and in the winter up to 30% more.German Federal Department of Highways, 1 Sept 2010"

I'm sorry, I forgot that it's 2051, not 2086. Yep, this one didn't come true either. And besides, the German department of highways is clearly the foremost authority on climate.

"Both theory and data say that global warming is likely to shrink deserts, not expand them, since greater ocean evaporation leads to more rainfall."

Show us the theory and data claims global warming is likely to shrink deserts.

I have a very specific question for you. Take out a map and located the following deserts in the world. Sonoran, Sahara and Arabian in the north. The Atacama, Kalahari and Australian in the South. What do they have in common?

David in Cal wrote:"There have been a large number of failed climate predictions. This site lists 107 of them, as of 2014. http://wattsupwiththat.com/2014/04/02/the-big-list-of-failed-climate-predictions/"

That list is as worthless as everything else on WUWT. No evidence is provided against any of them= items. The list also reacts as if 5 years is long enough to prove or falsify a statement (#2) like "Milder winters, drier summers: Climate study shows a need to adapt in Saxony Anhalt."

For example, in what way has #1 been shown false? "“Due to global warming, the coming winters in the local regions will become milder.”

Only a denier would take this list seriously. And those are the only peopel it was written for.

DiC wrote:"The UNEP spokesman said land degradation, the loss of forests and other environmental changes were accelerating. In fact, forested land has been increasing, not shrinking."

Your evidence?

"The world's forests continue to shrink as populations increase and forest land is converted to agriculture and other uses, but over the past 25 years the rate of net global deforestation has slowed down by more than 50 percent, FAO said in a report published today."9/7/15http://www.fao.org/news/story/en/item/326911/icode/

Joe T -- be serious. You know as well as I do that you could look up these predictions via google, if you wanted to take the trouble. Same for rainfall and deserts. However, I will give you a couple of links.

Regarding rainfall, a climate catastrophist site wrote, "A warmer climate spurs the evaporation of water from land and sea and allows the atmosphere to hold more moisture—thus setting the stage for more extreme precipitation." http://www.climatehotmap.org/global-warming-effects/rain-and-snow.html

David -- Who should we believe? Here's a recent article from the Washington Post, Planet Earth is actually getting greener — but that might not be a good thing https://www.washingtonpost.com/news/morning-mix/wp/2015/04/10/planet-earth-is-actually-getting-greener-but-that-might-not-be-a-good-thing/

DiC: People who claim something (here, that certain predictions have not come true, even predictions for 2050, 2086, etc) have the obligation to prove it. This list doesn't do that at all. Telling someone to just use Google is useless -- Google is hardly the arbiteur of all things. This list is useless and simple propaganda written for people who won't, or don't know have, to think and ask questions.

Frankly David I'm very tired of correcting you time and time and time again on obvious stuff just like this. You make claims but never provide evidence, just like this list does.

You've become a waste of time here and a distraction from the discussion of science. As someone said awhile back, climate science needs better skeptics.

First you post nonsense "failed predictions" that you obviously didn't even take the time to read, now you point to a Union of Concerned Scientist's web site and you fail to understand what it is they are actually saying.

"Regarding rainfall, a climate catastrophist site wrote, "A warmer climate spurs the evaporation of water from land and sea and allows the atmosphere to hold more moisture—thus setting the stage for more extreme precipitation." http://www.climatehotmap.org/global-warming-effects/rain-and-snow.html"

Here's the part you left out:"However, wet places tend to get wetter and dry places dryer in a warming world—as is already occurring today."

When the global temperature increases, the hydrological cycle changes. I asked you before what the deserts I listed have in common? Why are they there?

Instead of linking to web sites, show me published papers. Like the increased drought in the Mediterranean (Hoerling AMS 2012) or that increased evapotranspiration increased the severity of the California drought (Seager AMS 2015).

"On FAR sea level projection, note that the "Business as Usual" scenario assumed substantial continuing increases in CFCs and methane, which largely didn't happen. The total historical forcing level to 2015 under this (GHG-only) scenario is about 30% greater than currently understood observed GHG forcing at 2015, and the observed forcing change from 1985 to 2015 is about 50% of that used in the scenario."

Paul, this is an excellent point. Can you point me to the source?

From Rahmstorf ERL (2012)"The rate of sea-level rise of the past few decades, on the other hand, is greater than projected by the IPCC models. This suggests that IPCC sea-level projections for the future may also be biased low."

So somewhere along the line, the IPCC revised its estimate of the forcing downward so that by TAR sea level rise was greater than projected? Is that the takeaway? What role did glacial melt play in the discrepancy?

The theory is that warmer temperatures lead to more ocean evaporation, which leads to more rain. Also, higher atmospheric CO2 not only helps plants grow, it helps them grow using less water.

Here's an excerpt from relevant article. The entire article is worth reading.

An increasingly rich trove of data suggest that in large parts of the world, the more likely outcome is that warmer temperatures lead to more rainfall, richer plant growth, and the re-greening of areas that have been inhospitable for many centuries.

Farming is expanding again in frosty Greenland, which got its name because farming was possible when the Vikings first settled there during the “Medieval Warm Period,” a previous phase of global warming. In the Alps, the tree line--meaning the altitude above which trees no longer grow because of the cold and wind--has been steadily rising, with forests growing thicker, according to researchers at the Swiss Institute for Forest, Snow and Avalanche Research in Davos. In arid Namibia, stuck between the Namib and the Kalahari Deserts, farmers say the last decade has seen increased rainfall, higher grass, and more of the wildlife that feeds on it.

In the latest issue of Nature, a U.S. Department of Agriculture study discovered that the higher temperatures and CO2 levels forecast by the IPCC boost the growth of prairie grass, a surprising find that suggests a greener, more fertile future for the world’s semi-arid grasslands, which cover one-third of the global land mass.

Widely reported scenarios that higher temperatures will dry out the Amazon rain forest also seem to be contradicted by evidence assembled by Smithsonian researcher Carlos Jamarillo. Jamarillo has studied the fossilized remains of ancient rainforests and concludes that warmer temperatures went hand-in-hand with greater plant growth and higher species diversity. It was the opposite of what the researchers expected.

"In the latest issue of Nature, a U.S. Department of Agriculture study discovered that the higher temperatures and CO2 levels forecast by the IPCC boost the growth of prairie grass, a surprising find that suggests a greener, more fertile future for the world’s semi-arid grasslands, which cover one-third of the global land mass."

From the Daily Beast article as quoted above,"Farming is expanding again in frosty Greenland, which got its name because farming was possible when the Vikings first settled there during the “Medieval Warm Period,” a previous phase of global warming."

"Palaeoclimate records spanning the past millennium are often characterized as including some manifestation of a warm Medieval Warm Period (MWP) followed by a cool Little Ice Age (LIA). Previous reviews of these intervals have shown a tendency for centennial-scale temperature anomalies, but have also emphasized their heterogeneity through space and time. Our regional temperature reconstructions (Fig. 2) also show little evidence for globally synchronized multi-decadal shifts that would mark well-defined worldwide MWP and LIA intervals."

"The problems of the famine-prone Sahel zone--the dry belt running across Africa on the southern edge of the Sahara--seem to have much less to do with weather than the fact that the population has roughly tripled since the 1950s, and with the arrival of millions of goats with their destructive grazing habits (unlike native camels or gazelles, goats rip out the entire plant, roots and all, killing vegetation wherever they go)"

This is written in such a confusing manner that one must ask whether it was done this way on purpose. What we expect to see in a warming world is a drying of the region north of the Sahara. Indeed the paper by Hoerling, "On the Increased Frequency of Mediterranean Drought" clearly supports this. It's the region south of the Sahara, the Sahel, that's more complex.

There may be some small component to drought in the Sahel that is due to overgrazing, but the main component is due to precipitation. It's the amount of precipitation that becomes highly variable due to a combination of sea surface temperatures and the location of the Intertropical Convergence Zone. Anthropogenic aerosols also play a role.

"The drying trend in the ensemble mean of the model simulations is attributable to anthropogenic forcing, partly to an increase in aerosol loading and partly to an increase in greenhouse gases. The model projects a drier Sahel in the future, due primarily to increasing greenhouse gases."

DA: 'Well, it's not 2030 yet, but Aviso data on sea level show an average rate of (linear) change for the 22.8 years of their data (1993.00 to 10/25/15) is 3.34 mm/yr. So for the 45 years considered in the FAR above, that works out to a projection (if linear) of 15.0 cm.'

13.7 cm. You're forgetting the GIA of +0.3 mm/yr used by that dataset.

Me too. My quibble was based on an assumption that it was the totals in Table 9.10 that didn't include GIA adjustments - that they were for what you might call 'actual' GMSL - and were thus incompatible with the 'actual' + 0.3 mm/yr AVISO numbers. I've skimmed Chapter 9 and I think I was wrong. The simplest interpretation of the estimates in Table 9.10 is that they had nothing to say about GIA, so are compatible with the AVISO numbers, which include GIA-driven growth of the ocean basins and an adjustment to get rid of it, netting out at (in effect) nothing to say about GIA. Quibble withdrawn. As you were.

But perhaps you can help me with a tangent that's making my brain hurt. Chapter 9 says that in those days they had such a poor handle on GIA that all they could do was hope that 'the net contribution of land movements [at tide-gauges] reduces to zero'. If it did, would that have anything to say about the size of the ocean basins? Would it necessarily mean that the bathtub was neither shrinking nor growing, so no GIA adjustment was required? My guess is no.